Performance analysis of a novel adiabatic compressed air energy system with ejectors enhanced charging process

Abstract

In an adiabatic compressed air energy storage system (A-CAES) with isochoric air storage tank, the throttle valve downstream the compressor results in large irreversible loss. In this paper, a novel A-CAES with ejectors in the charging process (ECA-CAES) is proposed to reduce throttling loss and enhance system performance. A thermodynamics model and an exergy calculation model of an ECA-CAES are established. By simulation, the influences of entrainment ratio, heat transfer temperature difference at cooling/heating exchangers and initial storage pressure on system performance are investigated. The simulation results show that a smaller entrainment ratio, a lower initial storage pressure or a smaller heat transfer temperature difference could more obviously improve the system performance. Compared with A-CAES system, the maximum roundtrip efficiency improvement of the proposed system is up to 2.34%, the maximum charge time, energy consumption of compressors and ratio of exergy destruction improvement in charging process are up to 3.63%, 3.64%, 3.85%, respectively. The exergy analysis depicts that the introduction of ejectors decreases the exergy destruction of the CAES, especially the irreversible loss in throttling valve and compressors. Hence, the proposed system is verified to be an effective way to improve the efficiency of compressed air energy storage system.